Magnetic Josephson Junctions With Superconducting Interlayer for Cryogenic Memory

作者：Vernik Igor V^*; Bol' ginov Vitaly V; Bakurskiy Sergey V; Golubov Alexander A; Kupriyanov Mikhail Yu; Ryazanov Valery V; Mukhanov Oleg A

来源：IEEE Transactions on Applied Superconductivity, 2013, 23(3): 1701208.

DOI：10.1109/TASC.2012.2233270

• Energy efficient
• memory devices
• proximity effect
• RAM
• single flux quantum
• superconducting logic elements

We investigate a Magnetic Josephson Junction (MJJ) - a superconducting device with ferromagnetic barrier for a scalable high-density cryogenic memory compatible with energy-efficient single flux quantum (SFQ) circuits. The superconductor-insulator-superconductor-ferromagnet-superconductor (SIS%26apos;FS) MJJs are analyzed both experimentally and theoretically. We found that the properties of SIS%26apos;FS junctions fall into two distinct classes based on the thickness of S%26apos; layer. We fabricate Nb-Al/AlOx-Nb-PdFe-Nb SIS%26apos;FS MJJs using a co-processing approach with a combination of HYPRES and ISSP fabrication processes. The resultant SIS%26apos;FS structure with thin superconducting S%26apos;-layer is substantially affected by the ferromagnetic layer as a whole. We fabricate these type of junctions to reach the device compatibility with conventional SIS junctions used for superconducting SFQ electronics to ensure a seamless integration of MJJ-based circuits and SIS JJ-based ultra-fast digital SFQ circuits. We report experimental results for MJJs, demonstrating their applicability for superconducting memory and digital circuits. These MJJs exhibit IcRn product only similar to 30% lower than that of conventional SIS junctions co-produced in the same fabrication. Analytical calculations for these SIS%26apos;FS structures are in a good agreement with the experiment. We discuss application of MJJ devices for memory and programmable logic circuits.

• 出版日期2013-6